oracle.toplink.essentials.internal.helper.TopLinkIdentityHashMap Maven / Gradle / Ivy
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package oracle.toplink.essentials.internal.helper;
/**
* INTERNAL:
*
* Purpose: Define a {@link Map} that manages key equality by reference,
* not equals(). This is required to track objects throughout the lifecycle
* of a {@link oracle.toplink.essentials.sessions.UnitOfWork}, regardless if the domain
* object redefines its equals() method. Additionally, this implementation does
* not permit nulls.
*
* @author Mike Norman (since TopLink 10.1.3)
*
*/
// J2SE imports
import java.io.*;
import java.util.*;
public class TopLinkIdentityHashMap extends AbstractMap implements Map, Cloneable, Serializable {
static final long serialVersionUID = -5176951017503351630L;
// the default initial capacity
static final int DEFAULT_INITIAL_CAPACITY = 32;
// the maximum capacity.
static final int MAXIMUM_CAPACITY = 1 << 30;
// the loadFactor used when none specified in constructor.
static final float DEFAULT_LOAD_FACTOR = 0.75f;
protected transient Entry[] entries;// internal array of Entry's
protected transient int count = 0;
private transient int modCount = 0;// # of times this Map has been modified
protected int threshold = 0;
protected float loadFactor = 0;
/**
* Constructs a new TopLinkIdentityHashMap with the given
* initial capacity and the given loadFactor.
*
* @param initialCapacity the initial capacity of this
* TopLinkIdentityHashMap.
* @param loadFactor the loadFactor of the TopLinkIdentityHashMap.
* @throws IllegalArgumentException if the initial capacity is less
* than zero, or if the loadFactor is nonpositive.
*/
public TopLinkIdentityHashMap(int initialCapacity, float loadFactor) {
if (initialCapacity < 0) {
throw new IllegalArgumentException("Illegal initialCapacity: " + initialCapacity);
}
if (initialCapacity > MAXIMUM_CAPACITY) {
initialCapacity = MAXIMUM_CAPACITY;
}
if ((loadFactor <= 0) || Float.isNaN(loadFactor)) {
throw new IllegalArgumentException("Illegal loadFactor: " + loadFactor);
}
// Find a power of 2 >= initialCapacity
int capacity = 1;
while (capacity < initialCapacity) {
capacity <<= 1;
}
this.loadFactor = loadFactor;
threshold = (int)(capacity * loadFactor);
entries = new Entry[capacity];
}
/**
* Constructs a new TopLinkIdentityHashMap with the given
* initial capacity and a default loadFactor of 0.75.
*
* @param initialCapacity the initial capacity of the
* TopLinkIdentityHashMap.
* @throws IllegalArgumentException if the initial capacity is less
* than zero.
*/
public TopLinkIdentityHashMap(int initialCapacity) {
this(initialCapacity, DEFAULT_LOAD_FACTOR);
}
/**
* Constructs a new TopLinkIdentityHashMap with a default initial
* capacity of 32 and a loadfactor of 0.75.
*/
public TopLinkIdentityHashMap() {
loadFactor = DEFAULT_LOAD_FACTOR;
threshold = (int)(DEFAULT_INITIAL_CAPACITY * DEFAULT_LOAD_FACTOR);
entries = new Entry[DEFAULT_INITIAL_CAPACITY];
}
/**
* Constructs a new TopLinkIdentityHashMap with the same mappings
* as the given map. The TopLinkIdentityHashMap is created with a
* capacity sufficient to hold the elements of the given map.
*
* @param m the map whose mappings are to be placed in the
* TopLinkIdentityHashMap.
*/
public TopLinkIdentityHashMap(Map m) {
this(Math.max((int)(m.size() / DEFAULT_LOAD_FACTOR) + 1, DEFAULT_INITIAL_CAPACITY), DEFAULT_LOAD_FACTOR);
putAll(m);
}
/**
* @return the size of this TopLinkIdentityHashMap.
*/
public int size() {
return count;
}
/**
* @return true if this TopLinkIdentityHashMap is empty.
*/
public boolean isEmpty() {
return (count == 0);
}
/**
* Returns true if this TopLinkIdentityHashMap contains
* the given object. Equality is tested by the equals() method.
*
* @param obj the object to find.
* @return true if this TopLinkIdentityHashMap contains
* obj.
* @throws NullPointerException if obj is null.
*/
public boolean containsValue(Object obj) {
if (obj == null) {
throw new NullPointerException();
}
Entry[] copyOfEntries = entries;
for (int i = copyOfEntries.length; i-- > 0;) {
for (Entry e = copyOfEntries[i]; e != null; e = e.next) {
if (e.value.equals(obj)) {
return true;
}
}
}
return false;
}
/**
* Returns true if this TopLinkIdentityHashMap contains a
* mapping for the given key. Equality is tested by reference.
*
* @param key object to be used as a key into this
* TopLinkIdentityHashMap.
* @return true if this TopLinkIdentityHashMap contains a
* mapping for key.
*/
public boolean containsKey(Object key) {
Entry[] copyOfEntries = entries;
int hash = System.identityHashCode(key);
int index = (hash & 0x7FFFFFFF) % copyOfEntries.length;
for (Entry e = copyOfEntries[index]; e != null; e = e.next) {
if (e.key == key) {
return true;
}
}
return false;
}
/**
* Returns the value to which the given key is mapped in this
* TopLinkIdentityHashMap. Returns null if this
* TopLinkIdentityHashMap contains no mapping for this key.
*
* @return the value to which this TopLinkIdentityHashMap maps the
* given key.
* @param key key whose associated value is to be returned.
*/
public Object get(Object key) {
Entry[] copyOfEntries = entries;
int hash = System.identityHashCode(key);
int index = (hash & 0x7FFFFFFF) % copyOfEntries.length;
for (Entry e = copyOfEntries[index]; e != null; e = e.next) {
if (e.key == key) {
return e.value;
}
}
return null;
}
/**
* INTERNAL:
* Re-builds the internal array of Entry's with a larger capacity.
* This method is called automatically when the number of objects in this
* TopLinkIdentityHashMap exceeds its current threshold.
*/
private void rehash() {
int oldCapacity = entries.length;
Entry[] oldEntries = entries;
int newCapacity = (oldCapacity * 2) + 1;
Entry[] newEntries = new Entry[newCapacity];
modCount++;
threshold = (int)(newCapacity * loadFactor);
entries = newEntries;
for (int i = oldCapacity; i-- > 0;) {
for (Entry old = oldEntries[i]; old != null;) {
Entry e = old;
old = old.next;
int index = (e.hash & 0x7FFFFFFF) % newCapacity;
e.next = newEntries[index];
newEntries[index] = e;
}
}
}
/**
* Associate the given object with the given key in this
* TopLinkIdentityHashMap, replacing any existing mapping.
*
* @param key key to map to given object.
* @param obj object to be associated with key.
* @return the previous object for key or null if this
* TopLinkIdentityHashMap did not have one.
* @throws NullPointerException if obj is null.
*/
public Object put(Object key, Object obj) {
if (obj == null) {
throw new NullPointerException();
}
Entry[] copyOfEntries = entries;
int hash = System.identityHashCode(key);
int index = (hash & 0x7FFFFFFF) % copyOfEntries.length;
for (Entry e = copyOfEntries[index]; e != null; e = e.next) {
if (e.key == key) {
Object old = e.value;
e.value = obj;
return old;
}
}
modCount++;
if (count >= threshold) {
rehash();
copyOfEntries = entries;
index = (hash & 0x7FFFFFFF) % copyOfEntries.length;
}
Entry e = new Entry(hash, key, obj, copyOfEntries[index]);
copyOfEntries[index] = e;
count++;
return null;
}
/**
* Removes the mapping (key and its corresponding value) from this
* TopLinkIdentityHashMap, if present.
*
* @param key key whose mapping is to be removed from the map.
* @return the previous object for key or null if this
* TopLinkIdentityHashMap did not have one.
*/
public Object remove(Object key) {
Entry[] copyOfEntries = entries;
int hash = System.identityHashCode(key);
int index = (hash & 0x7FFFFFFF) % copyOfEntries.length;
for (Entry e = copyOfEntries[index], prev = null; e != null; prev = e, e = e.next) {
if (e.key == key) {
if (prev != null) {
prev.next = e.next;
} else {
copyOfEntries[index] = e.next;
}
count--;
return e.value;
}
}
return null;
}
/**
* Copies all of the mappings from the given map to this
* TopLinkIdentityHashMap, replacing any existing mappings.
*
* @param m mappings to be stored in this TopLinkIdentityHashMap.
* @throws NullPointerException if m is null.
*/
public void putAll(Map m) {
if (m == null) {
throw new NullPointerException();
}
Iterator i = m.entrySet().iterator();
while (i.hasNext()) {
Map.Entry me = (Map.Entry)i.next();
put(me.getKey(), me.getValue());
}
}
/**
* Removes all of the mappings from this TopLinkIdentityHashMap.
*/
public void clear() {
if (count > 0) {
modCount++;
Entry[] copyOfEntries = entries;
for (int i = copyOfEntries.length; --i >= 0;) {
copyOfEntries[i] = null;
}
count = 0;
}
}
/**
* Returns a shallow copy of this TopLinkIdentityHashMap (the
* elements are not cloned).
*
* @return a shallow copy of this TopLinkIdentityHashMap.
*/
public Object clone() {
try {
Entry[] copyOfEntries = entries;
TopLinkIdentityHashMap clone = (TopLinkIdentityHashMap)super.clone();
clone.entries = new Entry[copyOfEntries.length];
for (int i = copyOfEntries.length; i-- > 0;) {
clone.entries[i] = (copyOfEntries[i] != null) ? (Entry)copyOfEntries[i].clone() : null;
}
clone.keySet = null;
clone.entrySet = null;
clone.values = null;
clone.modCount = 0;
return clone;
} catch (CloneNotSupportedException e) {
// this shouldn't happen, since we are Cloneable
throw new InternalError();
}
}
// Views - the following is standard 'boiler-plate' Map stuff
private transient Set keySet = null;
private transient Set entrySet = null;
private transient Collection values = null;
/**
* Returns a set view of the keys contained in this
* TopLinkIdentityHashMap. The set is backed by the map, so
* changes to the map are reflected in the set, and vice versa. The set
* supports element removal, which removes the corresponding mapping from
* this map, via the Iterator.remove, Set.remove,
* removeAll, retainAll, and clear operations.
* It does not support the add or addAll operations.
*
* @return a set view of the keys contained in this
* TopLinkIdentityHashMap.
*/
public Set keySet() {
if (keySet == null) {
keySet = new AbstractSet() {
public Iterator iterator() {
return getHashIterator(KEYS);
}
public int size() {
return count;
}
public boolean contains(Object o) {
return containsKey(o);
}
public boolean remove(Object o) {
int oldSize = count;
TopLinkIdentityHashMap.this.remove(o);
return count != oldSize;
}
public void clear() {
TopLinkIdentityHashMap.this.clear();
}
};
}
return keySet;
}
/**
* Returns a collection view of the values contained in this
* TopLinkIdentityHashMap. The collection is backed by the map, so
* changes to the map are reflected in the collection, and vice versa. The
* collection supports element removal, which removes the corresponding
* mapping from this map, via the Iterator.remove,
* Collection.remove, removeAll, retainAll, and
* clear operations. It does not support the add or
* addAll operations.
*
* @return a collection view of the values contained in this
* TopLinkIdentityHashMap.
*/
public Collection values() {
if (values == null) {
values = new AbstractCollection() {
public Iterator iterator() {
return getHashIterator(VALUES);
}
public int size() {
return count;
}
public boolean contains(Object o) {
return containsValue(o);
}
public void clear() {
TopLinkIdentityHashMap.this.clear();
}
};
}
return values;
}
/**
* Returns a collection view of the mappings contained in this
* TopLinkIdentityHashMap. Each element in the returned collection
* is a Map.Entry. The collection is backed by the map, so changes
* to the map are reflected in the collection, and vice versa. The
* collection supports element removal, which removes the corresponding
* mapping from the map, via the Iterator.remove,
* Collection.remove, removeAll, retainAll, and
* clear operations. It does not support the add or
* addAll operations.
*
* @return a collection view of the mappings contained in this
* TopLinkIdentityHashMap.
*/
public Set entrySet() {
if (entrySet == null) {
entrySet = new AbstractSet() {
public Iterator iterator() {
return getHashIterator(ENTRIES);
}
public boolean contains(Object o) {
if (!(o instanceof Map.Entry)) {
return false;
}
Map.Entry entry = (Map.Entry)o;
Object key = entry.getKey();
Entry[] copyOfEntries = entries;
int hash = System.identityHashCode(key);
int index = (hash & 0x7FFFFFFF) % copyOfEntries.length;
for (Entry e = copyOfEntries[index]; e != null; e = e.next) {
if ((e.hash == hash) && e.equals(entry)) {
return true;
}
}
return false;
}
public boolean remove(Object o) {
if (!(o instanceof Map.Entry)) {
return false;
}
Map.Entry entry = (Map.Entry)o;
Object key = entry.getKey();
Entry[] copyOfEntries = entries;
int hash = System.identityHashCode(key);
int index = (hash & 0x7FFFFFFF) % copyOfEntries.length;
for (Entry e = copyOfEntries[index], prev = null; e != null;
prev = e, e = e.next) {
if ((e.hash == hash) && e.equals(entry)) {
modCount++;
if (prev != null) {
prev.next = e.next;
} else {
copyOfEntries[index] = e.next;
}
count--;
e.value = null;
return true;
}
}
return false;
}
public int size() {
return count;
}
public void clear() {
TopLinkIdentityHashMap.this.clear();
}
};
}
return entrySet;
}
private Iterator getHashIterator(int type) {
if (count == 0) {
return emptyHashIterator;
} else {
return new HashIterator(type);
}
}
/**
* TopLinkIdentityHashMap entry.
*/
private static class Entry implements Map.Entry {
int hash;
Object key;
Object value;
Entry next;
Entry(int hash, Object key, Object value, Entry next) {
this.hash = hash;
this.key = key;
this.value = value;
this.next = next;
}
protected Object clone() {
return new Entry(hash, key, value, ((next == null) ? null : (Entry)next.clone()));
}
// Map.Entry Ops
public Object getKey() {
return key;
}
public Object getValue() {
return value;
}
public Object setValue(Object value) {
Object oldValue = this.value;
this.value = value;
return oldValue;
}
public boolean equals(Object o) {
if (!(o instanceof Map.Entry)) {
return false;
}
Map.Entry e = (Map.Entry)o;
return (key == e.getKey()) && ((value == null) ? (e.getValue() == null) : value.equals(e.getValue()));
}
public int hashCode() {
return hash ^ ((value == null) ? 0 : value.hashCode());
}
public String toString() {
return key + "=" + value;
}
}
// Types of Iterators
private static final int KEYS = 0;
private static final int VALUES = 1;
private static final int ENTRIES = 2;
private static EmptyHashIterator emptyHashIterator = new EmptyHashIterator();
private static class EmptyHashIterator implements Iterator {
EmptyHashIterator() {
}
public boolean hasNext() {
return false;
}
public Object next() {
throw new NoSuchElementException();
}
public void remove() {
throw new IllegalStateException();
}
}
private class HashIterator implements Iterator {
Entry[] entries = TopLinkIdentityHashMap.this.entries;
int index = entries.length;
Entry entry = null;
Entry lastReturned = null;
int type;
/**
* The modCount value that the iterator believes that the backing
* List should have. If this expectation is violated, the iterator
* has detected concurrent modification.
*/
private int expectedModCount = modCount;
HashIterator(int type) {
this.type = type;
}
public boolean hasNext() {
Entry e = entry;
int i = index;
Entry[] copyOfEntries = TopLinkIdentityHashMap.this.entries;
while ((e == null) && (i > 0)) {
e = copyOfEntries[--i];
}
entry = e;
index = i;
return e != null;
}
public Object next() {
if (modCount != expectedModCount) {
throw new ConcurrentModificationException();
}
Entry et = entry;
int i = index;
Entry[] copyOfEntries = TopLinkIdentityHashMap.this.entries;
while ((et == null) && (i > 0)) {
et = copyOfEntries[--i];
}
entry = et;
index = i;
if (et != null) {
Entry e = lastReturned = entry;
entry = e.next;
return (type == KEYS) ? e.key : ((type == VALUES) ? e.value : e);
}
throw new NoSuchElementException();
}
public void remove() {
if (lastReturned == null) {
throw new IllegalStateException();
}
if (modCount != expectedModCount) {
throw new ConcurrentModificationException();
}
Entry[] copyOfEntries = TopLinkIdentityHashMap.this.entries;
int index = (lastReturned.hash & 0x7FFFFFFF) % copyOfEntries.length;
for (Entry e = copyOfEntries[index], prev = null; e != null; prev = e, e = e.next) {
if (e == lastReturned) {
modCount++;
expectedModCount++;
if (prev == null) {
copyOfEntries[index] = e.next;
} else {
prev.next = e.next;
}
count--;
lastReturned = null;
return;
}
}
throw new ConcurrentModificationException();
}
}
/**
* Serialize the state of this TopLinkIdentityHashMap to a stream.
*
* @serialData The capacity of the TopLinkIdentityHashMap
* (the length of the bucket array) is emitted (int), followed by the
* size of the TopLinkIdentityHashMap, followed by the
* key-value mappings (in no particular order).
*/
private void writeObject(ObjectOutputStream s) throws IOException {
// Write out the threshold, loadfactor (and any hidden 'magic' stuff).
s.defaultWriteObject();
// Write out number of buckets
s.writeInt(entries.length);
// Write out count
s.writeInt(count);
// Write out contents
for (int i = entries.length - 1; i >= 0; i--) {
Entry entry = entries[i];
while (entry != null) {
s.writeObject(entry.key);
s.writeObject(entry.value);
entry = entry.next;
}
}
}
/**
* Deserialize the TopLinkIdentityHashMap from a stream.
*/
private void readObject(ObjectInputStream s) throws IOException, ClassNotFoundException {
// Read in the threshold, loadfactor (and any hidden 'magic' stuff).
s.defaultReadObject();
// Read in number of buckets and allocate the bucket array;
int numBuckets = s.readInt();
entries = new Entry[numBuckets];
// Read in size (count)
int size = s.readInt();
// Read the mappings and add to the TopLinkIdentityHashMap
for (int i = 0; i < size; i++) {
Object key = s.readObject();
Object value = s.readObject();
put(key, value);
}
}
}